Biomass fuel compact processing method

ABSTRACT

A method of processing a biomass fuel compact is provided by the present disclosure that includes comprising combining a composition of combustible biomass materials, comminuting the composition of biomass materials, drying the comminuted composition of biomass materials, and adding an adhesive to the biomass materials, the adhesive comprising a starch and a hydroxide. Further additives are also provided, which include a silicate, a viscosity agent, a preservative, and a BTU additive. The composite biomass is processed into a shapeform, and then the shapeform is partitioned into individual pieces that are compatible with existing powerplants. In one form, the processing is performed at lower temperatures such that an endothermic reaction of the biomass materials and adhesive results.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon Provisional Patent Application Ser. No. 61/336,989, entitled “Improved Biomass Fuel Pellet,” filed Jan. 29, 2010, the contents of which are incorporated herein by reference in their entirety and continued preservation of which is requested. This application is also related to the application “Composite Biomass Fuel Compact” filed concurrently herewith, which is commonly assigned with the present application, and the contents of which are incorporated herein by reference in their entirety.

FIELD

The present disclosure relates to renewable energy sources, and in particular, resources that do not depend on fossil fuels and that reduce emissions of “greenhouse gas” carbon dioxide into the atmosphere. More specifically, the present disclosure relates to manufacturing processes for creating combustible biomass, or biofuel materials.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

With the recent emphasis on renewable energy sources, efforts have been made in the art to create so-called “biomass” materials, in which a combustible combination of waste, such as wood chips or sawdust, along with certain additives, are combined and processed to create an energy resource that can take the place of, or be combined with, for example, coal. A common biomass is the wood pellet, which is now subject to a standard developed by the Pellet Fuels Institute. Wood pellets are generally manufactured using pellet presses or pellet mills. These devices use compression to force wood particles through metal dies or molds. In some machines, pressure is applied discontinuously by the action of a piston on material packed into a cylinder. The equipment may have a mechanical coupling and fly wheel or utilize hydraulic action on the piston.

Known biomass materials have included natural lignins of the constituent materials in order to bind the materials together during the manufacturing process, in order to create a burnable mass. Natural lignins, for example from various wood sources, are complex natural polymers resulting from oxidative coupling of, primarily, 4-hydroxyphenylpropanoids. Additionally, other materials such as thermoplastic resins have been added in the manufacturing process to bind the constituent materials together.

However, these natural lignins and thermoplastic binders do not create a biomass that is durable for transport or other processing operations, especially using known manufacturing techniques such as those set forth above. As a result, various biomass forms suffer from chronic crumbling and dust generation during production and downstream handling. Significant amounts of dust can become an explosive issue, and thus current binders in the art may ultimately cause safety hazards. As a further disadvantage of known binders, product uniformity is an issue, with irregular lengths and ragged cuts, which further add to the dust problem. As other materials with lower or minimal natural lignins are added, such as switchgrass, forest litter, paper waste, cane waste, and the like, product quality is reduced, and the dust issue often becomes more aggravated. Additionally, some of the known binders generate gases during the burning process that are environmentally undesirable, and in fact, some of the binders are not completely combusted during the burning process. Therefore, current manufacturing processes, and the materials used therein, create biomass forms that are not durable and that cause issues in their manufacture and downstream handling.

SUMMARY

In one form of the present disclosure, a method of processing a biomass fuel compact is provided that comprises combining a composition of biomass materials, comminuting the composition of biomass materials, adding an adhesive to the biomass materials to form a composite biomass, the adhesive comprising a starch and a hydroxide, and forming the composite biomass into a shapeform.

In another form, a method of processing a biomass fuel compact is provided that comprises combining a composition of biomass materials, adding an adhesive to the biomass materials to form a composite biomass, the adhesive comprising a starch and a hydroxide, and forming the composite biomass into a shapeform.

In still another form, a method of processing a biomass fuel compact is provided that comprises combining a composition of biomass materials, comminuting the composition of biomass materials, drying the comminuted composition of biomass materials, adding an adhesive to the biomass materials, the adhesive comprising a starch and a hydroxide, adding a silicate to the composition of biomass materials, adding a viscosity agent to the composition of biomass materials to form a composite biomass, forming the composite biomass into a shapeform, and partitioning the composite biomass shapeform into individual pieces that are compatible with existing powerplants. The processing is performed at lower temperatures such that an endothermic reaction of the biomass materials and adhesive results.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a process flow diagram illustrating the various steps and forms of the manufacturing processes according to the teachings of the present disclosure.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

Referring to FIG. 1, manufacturing steps for processing a biomass fuel compact, and variations thereof, are shown. It should be understood that these steps may be carried out in order as shown, or alternately, in a different order. Therefore, the order of the steps illustrated should not be construed as limiting the scope of the present disclosure. In one form, the method of processing a biomass fuel compact comprises combining a composition of biomass materials. These biomass materials are essentially any combustible material, or combination of combustible materials. For example, these materials may include saw dust, cardboard and chipboard, grass, switchgrass, energy crops, hay, tree bark, sweetgum seed pods, pinecones, newsprint, wheat straw, duckweed, pine needles, mixed leaves, yard waste, agricultural waste, cotton waste, grape and wine offal, corn stover, crop stovers, peat, tobacco waste, tea waste, coffee waste, food processing waste, food packaging waste, nut meats and shells, chestnut hulls, pecan shells, animal waste, livestock waste, mammal waste, municipal solid waste, paper waste, pallets, and egg cartons, among others. Other combustible materials may also be employed, and thus these biomass materials should not be construed as limiting the scope of the present disclosure.

Next, these biomass materials may be comminuted, or crushed, to a particle size that is compatible with the specific process, and also with other additives and various processing steps, as set forth in greater detail below. The comminuted composition of biomass materials may next be dried, or alternately, the comminuted composition of biomass materials may be wet before entering a forming step, again depending on a variety of processing parameters. For example, if a tree or wood products were used as part of the biomass composition, then the comminuting step would take these materials down to a sawdust form. The comminution process may be carried out, for example, by tub grinders, horizontal grinders, hammer mills, burr mills, or shredders, among others. Each type of biomass material will have a different derived particle size from the comminuting step. Generally, particle size requirements are based on desired throughput rates. In one form of the present disclosure, a particle size that is about 20 to about 40%, and more particularly about 30%, of the die opening/diameter used to produce the desired shapeform. These particle sizes facilitate flow rates without excessive processing back-pressure.

If the biomass materials are dried before entering the forming step, a moisture content of about 8% to about 20%, and more specifically about 12%, is typical for many types of biomass materials. In one form of the present disclosure, the drying is performed by low cost solar collector troughs that concentrate solar energy and heat suitable thermal mediums such as oil, antifreeze, water, or a mixture thereof, for transmission of heat energy through liquid to air heat exchangers. Alternately, geothermal drying may be employed, alone or in combination with gas-fired or electric drying processes. Drying equipment may also be conventional grain drying batch hoppers, bins, or silos, or higher throughput horizontal dryers. Further still, heat may be transferred through a passive floor heating system. In yet another form, single or multiple desiccant beds may be employed to remove moisture from the drying air. It should be understood that these drying methods are merely exemplary and thus should not be construed as limiting the scope of the present disclosure.

An advantageous step of the present disclosure involves adding an adhesive to the biomass materials, wherein the adhesive comprises a starch and a hydroxide. This combination of the combustible biomass composition and the adhesive additive, along with other additives as described below and their proportions for mixing/processing, is set forth in greater detail in an application filed concurrently herewith titled “Composite Biomass Fuel Compact,” which is commonly assigned with the present application and the contents of which are incorporated by reference herein in their entirety.

In addition to the adhesive, further additives are also provided within the manufacturing process. These additives include, by way of example, a silicate, a viscosity agent, a preservative, and a BTU additive.

After or during the introduction of additives, the composite biomass is formed into a shapeform. In one form of the present disclosure, the forming step is performed by an extrusion process. Other manufacturing processes may also be employed, including but not limited to compression molding, plunger molding, and die forming. Therefore, the extrusion process should not be construed as limiting the scope of the present disclosure. In one desired form of the present disclosure, the extruder premixes, extrudes, and cuts to length a composite biomass fuel compact at about 500 to about 30,000 pounds per hour.

In one form, the innovative adhesive is added at a throat portion of the extruder. Alternately, the adhesive is added in a hopper portion of the extruder. In still another form, the adhesive is added in a die portion of the extruder and is configured to coat an exterior surface area of the composition of biomass materials. The adhesive may be further divided within the processing step, wherein the starch is mixed with the biomass composition prior to forming, and the hydroxide is added during the forming. Alternately, the hydroxilazed, gelled starch is added between the throat and before the forming die. Additionally, steam may be used as a processing aid during forming in order to provide for better physical properties of the biomass composition and additives.

With plunger molding, in one form the adhesive is added between wads of the plunger. Alternately, the adhesive is added at a plunger input and is configured to coat an exterior surface area of the composition of biomass materials at an exit die.

It is further contemplated that a mechanical briquetting process, such as the Brik Series by Dipiu Macchine Impianti, Italy, or BHS Energy LLC, Wyoming, Pa., USA, may be employed in accordance with the teachings of the present disclosure.

The shapeform of the composite biomass may be any number of geometric configurations, including but not limited to pellets, briquettes, pucks, and the innovative corn kernel configuration as described in the copending application set forth above.

After the composite biomass is produced as a shapeform, it is partitioned into individual pieces. The individual pieces may be the same size, or of varying sizes/lengths. In one form, the individual pieces are compatible with any existing powerplants. These existing powerplants comprise, by way of example, combustion, power generation, gasification, ethanol, digestion, and steam generation plants.

In one form of the present disclosure, the processing is performed at lower temperatures such that an endothermic reaction of the biomass materials and adhesive results. These temperatures are in the range of about 200 to about 250° C. for an extrusion process, and similarly, about 25 to about 200° C. for other plunger or flywheel processes.

It should be noted that the invention is not limited to the various forms described and illustrated as examples. A large variety of modifications have been described and more are part of the knowledge of the person skilled in the art. These and further modifications as well as any replacement by technical equivalents may be added to the description and figures, without leaving the scope of the protection of the disclosure and of the present patent. 

1. A method of processing a biomass fuel compact comprising: combining a composition of combustible biomass materials; comminuting the composition of biomass materials; adding an adhesive to the biomass materials to form a composite biomass, the adhesive comprising a starch and a hydroxide; and forming the composite biomass into a shapeform.
 2. The method according to claim 1, wherein the forming step is performed by one of the group consisting of extrusion, compression molding, plunger molding, and die forming.
 3. The method according to claim 1, wherein the composition of biomass materials are in a dry condition upon entering the forming step.
 4. The method according to claim 1, wherein the composition of biomass materials are in a wet condition upon entering the forming step.
 5. The method according to claim 1, wherein the processing is performed at lower temperatures such that an endothermic reaction of the biomass materials and adhesive results.
 6. The method according to claim 1 further comprising partitioning the extruded composite biomass into individual pieces after forming, wherein the individual pieces are compatible with existing processing plants.
 7. The method according to claim 6, wherein the processing plants comprise combustion, power generation, gasification, ethanol, digestion, and steam generation plants.
 8. The method according to claim 1, wherein the adhesive is added in the forming step.
 9. The method according to claim 1 further comprising adding at least one of a silicate, a viscosity agent, a preservative, and a BTU additive to the composition of biomass materials.
 10. A method of processing a biomass fuel compact comprising: combining a composition of combustible biomass materials; adding an adhesive to the biomass materials to form a composite biomass, the adhesive comprising a starch and a hydroxide; and forming the composite biomass into a shapeform.
 11. The method according to claim 10, wherein the forming step is performed by a plunger.
 12. The method according to claim 11, wherein the adhesive is added between wads of the plunger.
 13. The method according to claim 11, wherein the adhesive is added at a plunger input and is configured to coat an exterior surface area of the composition of biomass materials at an exit die.
 14. The method according to claim 10, wherein the forming step is performed by an extruder.
 15. The method according to claim 14, wherein the adhesive is added at a throat portion of the extruder.
 16. The method according to claim 14, wherein the adhesive is added in a hopper portion of the extruder.
 17. The method according to claim 14, wherein the adhesive is added in a die portion of the extruder and is configured to coat an exterior surface area of the composition of biomass materials.
 18. The method according to claim 10, wherein the starch is mixed with the biomass composition prior to forming, and the hydroxide is added during the forming.
 19. The method according to claim 10, wherein steam is used as a processing aid during forming.
 20. A method of processing a biomass fuel compact comprising: combining a composition of combustible biomass materials; comminuting the composition of biomass materials; drying the comminuted composition of biomass materials; adding an adhesive to the biomass materials, the adhesive comprising a starch and a hydroxide; adding a silicate to the composition of biomass materials; adding a viscosity agent to the composition of biomass materials to form a composite biomass; forming the composite biomass into a shapeform; and partitioning the composite biomass shapeform into individual pieces that are compatible with existing powerplants, wherein the processing is performed at lower temperatures such that an endothermic reaction of the biomass materials and adhesive results. 